The invention relates to an electrical switchgearand to a ventilation device having two ventilation elements.
An electrical switchgear usually comprises a number of function modules which are separate from one another. Usually provided inside these function modules are individual function spaces. The function spaces may be, for example, switching compartments, cable terminal compartments or busbar compartments. The components contained in these function spaces, in particular the cable and terminal leads, carry high currents and consequently are continuously generating heat. This must be carried away from the interior of the housing. Often provided in the function modules for this purpose are ventilation openings, through which cold air which carries heat away from the components can flow in and finally leaves the function module again through venting openings. In this case, the cooling may be achieved by free convection or by forced convection, for example with a fan. The ventilation and venting openings in this case remain constantly open. In the event that a fault-induced are flashover can occur within the function module, it is possible, for example, for hot gases to escape from the plant through such openings and injure the plant personnel or cause other damage. On the other hand, a solution without ventilation openings would require the function modules to have a very large volume of their own. This would, however, be counter to the requirement for a compact and consequently space-saving and low-cost design of the function modules.
It is known, in the case of an arc flashover, and excess pressure thereby occurring in the function module, to close the ventilation openings mentioned mechanically. The ensures that the hot gases and the pressure surge produced by the arc flashover are kept within the interior of the plant. For this purpose, the ventilation openings may be closed in the case of excess pressure by two non-return valves successively arranged and connected by a linkage. In this case, the movable element is fixed in the open position during normal operation by a thread which can easily melt. In the case of an arc flashover, with the great generation of heat accompanying it, the thread is destroyed and the movable element swings under the influence of gravity and the pressure surge on the linkage guide against the fixed element and closes the latterxe2x80x94whereas the venting openings are formed as decompression flaps provided with air slits.
It is also known to close the ventilation openings of a switchgear in the event of excess pressure by hinged flaps. During normal operation, the flaps are held in the open position by spring components. The pressure surge arising when there is an arc flashover causes the flaps to be released from their securement and slam onto the ventilation slits. Fixing in the closed position is not envisaged.
The invention relates to an electrical switchgear comprising at least one function module having an encapsulated housing and comprising a decompression channel which is connected to the housing, the decompression channel having a ventilation device in at least one of its generated surfaces, the device having two wall-like ventilation elements which are successively arranged at a distance from each other and are provided with ventilation openings, one ventilation element being connected in a fixed manner to the generated surface of the decompression channel and the other ventilation element being movable in a guided manner against the fixed ventilation element.
The invention also relates to a ventilation device comprising two wall-like ventilation elements which are successively arranged at a distance from each other and are provided with ventilation openings, one ventilation element being connected in a fixed manner to a wall surface of the device to be ventilated and the other ventilation element being movable in a guided manner against the fixed ventilation element.
Simply stated, the invention sproposes a ventilation device which is as simple as possible, saves space and can be produced at low cost, comprising ventilation openings which close in the event of excess pressure, the ventilation openings remaining closed over an adequately long period of time.
In one embodiment of the invention, the movable ventilation element is movable linearly inside a guiding frame, by the ventilation openings of the ventilation elements being staggered in relation to one another and by the movable ventilation element having spring-like catch elements with which engaging openings in the guiding frame are associated.
The ventilation device according to the invention has the advantage of a space-saving and additionally simple-to-produce construction. For example, the ventilation elements may comprise simply shaped metal sheets. During normal operation, the heated air can flow out of the plant through the ventilation openings arranged in the ventilation elements.
In the event of an arc with a subsequent excess pressure peak, the staggered ventilation openings are closed. In this regard, the movable ventilation element is moved against the fixed ventilation element and fixed there. On account of the staggered arrangement of the ventilation openings, they are closed in a sealed manner. The closing of the ventilation openings is initiated by the pressure peak itself, so that no further measures have to be taken for detecting the arc or for controlling the closure.
Since one ventilation element is movably configured, the number of parts which are movable, and consequently subject to wear, is reduced to a minimum. Consequently, low maintenance expenditure is incurred. The spring-like catch elements on the movable ventilation element serve, on the one hand, for the easily releasable fixing of the movable ventilation element in the open position. On the other hand, they arrest the movable element in the closed position. This measure achieves the effect that, even after the first pressure peak has subsided, the ventilation openings continue to remain securely closed. In this way, hot gases which are still included in the decompression channel even after the pressure peak cannot escape from the plant. The design with the spring-like catch elements makes it possible that, after a fault in the plant, the movable ventilation elements can be reset into their open position without great expenditure. No special tools are required for this purpose.
An advantageous embodiment of the invention includes the slidable guiding pins provided for guiding the movable ventilation element in guiding grooves.
This design permits secure guidance of the movable ventilation element and prevents canting of the ventilation elements.
A further advantageous embodiment of the invention provides that the ventilation openings are formed as slits.
The configuration of the ventilation openings in the form of slits can be easily realized in production engineering terms.
Ventilation devices such as those which, according to the invention, are integrated in the decompression channel of a switchgear may also be used if appropriate for other devices in which it is in certain cases a concern to keep pressure peaks or high temperatures within the device.